Apparatus for producing three-dimensional multilayer model, method for producing three-dimensional multilayer model, and flaw detector

ABSTRACT

A flaw detector that detects a flaw in a surface layer portion of a three-dimensional multilayer object during production. The flaw detector includes a probe extending in a second direction intersecting a first direction which is a scanning direction. The probe contains a plurality of coil units disposed side by side in the second direction and each of the coil units includes an excitation coil generating an eddy current in the surface layer portion, and a pair of detection coils disposed side by side inside the excitation coil.

CROSS-REFERENCE TO RELATED APPLICATIONS

This U.S. non-provisional patent application is a divisional of andclaims priority to U.S. patent application Ser. No. 16/616,660, filed onNov. 25, 2019, which is a 371 National Phase application claimingpriority to PCT/JP2018/020175, filed on May 25, 2018, which claimspriority under 35 U.S.C. § 119 of Japanese Patent Application No.2017-104684, filed May 26, 2017 in the Japanese Patent Office, theentire contents of which are hereby incorporated by reference.

TECHNICAL FIELD

The present disclosure relates to an apparatus for producing athree-dimensional multilayer object, a method for producing athree-dimensional multilayer object, and a flaw detector.

BACKGROUND ART

In the related art, there is an apparatus that produces athree-dimensional product by disposing powder, which is a raw material,in layers on a work table and sequentially melting powder layers byapplying energy to a selected portion of the powder layers (for example,refer to Patent Literature 1). The apparatus for producing athree-dimensional product produces three-dimensional products byrepeating following steps; partially melting one powder layer and curingthe molten powder, then forming another powder layer on the powderlayer, and further melting and curing a selected portion.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Unexamined Patent Publication No.2003-531034

SUMMARY OF INVENTION Technical Problem

However, in the related art, after the production of thethree-dimensional product has been completed, the three-dimensionalproduct is inspected. For this reason, if a flaw present inside thethree-dimensional product has been detected, it is not easy to repairthe flaw.

The present disclosure describes an apparatus for producing athree-dimensional multilayer object, a method for producing athree-dimensional multilayer object, and a flaw detector capable ofdetecting a flaw in a three-dimensional multilayer object during theproduction of the three-dimensional multilayer object.

Solution to Problem

According to one aspect of the present disclosure, there is provided anapparatus for producing a three-dimensional multilayer object whichproduces a three-dimensional multilayer object by partially applyingenergy to a conductive powder and thereby melting or sintering andcuring the conductive powder, the apparatus including: a holding unitholding the conductive powder, and holding the cured three-dimensionalmultilayer object; an energy application unit applying energy to alaminate of the conductive powder held by the holding unit; a probedisposed spaced apart upward from a surface layer portion of the curedthree-dimensional multilayer object and detecting a flaw in the surfacelayer portion; and a probe moving mechanism relatively moving the probewith respect to the surface layer portion. The probe contains anexcitation coil generating an eddy current in the surface layer portion,and a detection coil detecting a change in a magnetic field of thesurface layer portion.

Effects of Invention

According to the present disclosure, it is possible to detect a flaw ina three-dimensional multilayer object during the production of thethree-dimensional multilayer object.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic configuration view illustrating an apparatus forproducing a three-dimensional multilayer object of a first embodiment ofthe present disclosure.

a. FIG. 2 is a schematic configuration view illustrating a flawdetection device of the first embodiment of the present disclosure.

b. FIG. 3 is a view illustrating the disposition of a plurality of coilunits in a probe of the first embodiment of the present disclosure asseen from above.

c. FIG. 4 is a bottom view illustrating the coil unit of FIG. 3.

d. FIG. 5 is a view illustrating an example of flaw detection resultobtained by the flaw detection device.

e. FIG. 6 is a view illustrating an example of flaw detection resultobtained by the flaw detection device.

f. FIG. 7 is a flowchart illustrating a procedure of a method forproducing a three-dimensional multilayer object.

g. FIG. 8 is a view illustrating the disposition of a plurality of coilunits in a probe of a second embodiment of the present disclosure asseen from above.

h. FIG. 9 is a plan view illustrating a movement path of the probe ofthe second embodiment.

i. FIG. 10 is a plan view illustrating another movement path of theprobe.

j. FIG. 11 is a plan view illustrating an apparatus for producing athree-dimensional multilayer object of a third embodiment.

k. FIG. 12 is a plan view illustrating an apparatus for producing athree-dimensional multilayer object of a fourth embodiment.

l. FIG. 13 is a plan view illustrating an apparatus for producing athree-dimensional multilayer object of a fifth embodiment.

m. FIG. 14 is a cross-sectional view of the apparatus for producing athree-dimensional multilayer object illustrated in FIG. 13.

DESCRIPTION OF EMBODIMENTS

According to one aspect of the present disclosure, there is provided anapparatus for producing a three-dimensional multilayer object whichproduces a three-dimensional multilayer object by partially applyingenergy to a conductive powder and thereby melting or sintering andcuring the conductive powder, the apparatus including: a holding unitholding the conductive powder, and holding the cured three-dimensionalmultilayer object; an energy application unit applying energy to theconductive powder held by the holding unit; a probe disposed spacedapart from a surface layer portion of the cured three-dimensionalmultilayer object and detecting a flaw in the surface layer portion; anda probe moving mechanism relatively moving the probe with respect to thesurface layer portion. The probe contains an excitation coil generatingan eddy current in the surface layer portion, and a detection coildetecting a change in a magnetic field of the surface layer portion.

Since the apparatus for producing a three-dimensional multilayer objectof the present disclosure is capable of detecting a flaw in the surfacelayer portion of the three-dimensional multilayer object duringproduction by relatively moving the probe with respect to the surfacelayer portion in a scanning direction, it is possible to produce thethree-dimensional multilayer object by further adding the conductivepowder after having confirmed that there is no flaw in the surface layerportion. For example, if a flaw is detected in the surface layerportion, it is possible to produce the three-dimensional multilayerobject by repairing the flaw at that point of time and further addingthe conductive powder after the repair is completed. “Relatively movingthe probe with respect to the surface layer portion” contains “movingthe probe” and “moving the surface layer portion”. For example, it ispossible to move the surface layer portion by moving the holding unit.

The apparatus for producing a three-dimensional multilayer object may beconfigured to further include a regulation unit leveling an uppersurface of a laminate of the conductive powder held by the holding unit,and a regulation unit moving mechanism relatively moving the regulationunit with respect to the conductive powder. “Relatively moving theregulation unit with respect to the conductive powder” contains “movingthe regulation unit” and “moving the conductive powder”. For example, itis possible to move the conductive powder by moving the holding unit.

In some aspects, a bottom surface of the probe may be configured to bedisposed higher than a lower end of the regulation unit. Therefore, itis possible to detect a flaw in the surface layer portion in a statewhere the probe is reliably in no contact with the conductive powder.

In some aspects, the regulation unit moving mechanism may be configuredto serve also as the probe moving mechanism. Therefore, it is possibleto move the regulation unit and the probe by using the regulation unitmoving mechanism. It is possible to link the movement of the probe withthe movement of the regulation unit.

In some aspects, the probe may be configured to be disposed behind theregulation unit in a movement direction of the regulation unit.Therefore, after the upper surface of the laminate of the conductivepowder has been leveled by the regulation unit, the probe is allowed topass thereby.

In some aspects, the probe may be configured to be attached to theregulation unit. Therefore, it is possible to detect a flaw in thesurface layer portion by moving the probe along with the regulationunit, and thus it is not necessary to separately perform movement of theregulation unit and movement of the probe, and to shorten a productiontime of the entire process containing an inspection step.

According to one aspect of the present disclosure, there is provided amethod for producing a three-dimensional multilayer object in which athree-dimensional multilayer object is produced by partially applyingenergy to a conductive powder and thereby melting or sintering andcuring the conductive powder, the method including: an energyapplication step of applying energy to the conductive powder to melt orsinter the conductive powder; and a flaw detection step of detecting aflaw in a surface layer portion of the cured three-dimensionalmultilayer object by relatively moving a probe, which is disposed spacedapart from the surface layer portion, with respect to the surface layerportion. The flaw detection step contains an excitation step ofgenerating an eddy current in the surface layer portion, and a detectionstep of detecting a change in a magnetic field of the surface layerportion.

In the method for producing a three-dimensional multilayer object of thepresent disclosure, since it is possible to detect a flaw in the surfacelayer portion of the three-dimensional multilayer object duringproduction by relatively moving the probe with respect to the surfacelayer portion in a scanning direction, it is possible to produce thethree-dimensional multilayer object by further adding the conductivepowder after having confirmed that there is no flaw in the surface layerportion. For example, if a flaw is detected in the surface layerportion, it is possible to produce the three-dimensional multilayerobject by repairing the flaw at that point of time and further addingthe conductive powder after the repair is completed.

In some aspects, the method may further contain a step of leveling anupper surface of the conductive powder held by a holding unit byrelatively moving a regulation unit with respect to the conductivepowder. The flaw detection step may be executed when the step ofleveling is executed. In the flaw detection step, a flaw may be detectedin the surface layer portion by disposing a bottom surface of the probehigher than a lower end of the regulation unit and relatively moving theprobe along with the regulation unit with respect to the surface layerportion. Therefore, it is possible to detect a flaw in the surface layerportion in a state where the probe is reliably in no contact with theconductive powder. In the flaw detection step, a flaw may be detected inthe surface layer portion by disposing the probe behind the regulationunit in a relative movement direction of the regulation unit. Therefore,after the upper surface of the laminate of the conductive powder hasbeen leveled by the regulation unit, the probe is allowed to passthereby. After the energy application step has been executed a pluralityof times, the flaw detection step may be executed for the surface layerportion formed of a plurality of layers.

According to one aspect of the present disclosure, there is provided aflaw detector that detects a flaw in a surface layer portion of athree-dimensional multilayer object during production, the detectorincluding a probe extending in a second direction intersecting a firstdirection which is a scanning direction. The probe contains a pluralityof coil units disposed side by side in the second direction. Each of thecoil units includes an excitation coil generating an eddy current in thesurface layer portion, and a pair of detection coils disposed side byside inside the excitation coil.

The flaw detector of the present disclosure is capable of detectingflaws in a wide range in the second direction and reducing a flawdetection time by moving the probe in the scanning direction. Since aflaw may be detected in the surface layer portion of thethree-dimensional multilayer object during production, it is possible toproduce the three-dimensional multilayer object by further adding aconductive powder after having confirmed that there is no flaw in thesurface layer portion. For example, if a flaw is detected in the surfacelayer portion, it is possible to produce the three-dimensionalmultilayer object by repairing the flaw at that point of time andfurther adding the conductive powder after the repair is completed.Therefore, it is not necessary to repair a flaw inside thethree-dimensional multilayer object after the production of thethree-dimensional multilayer object has been completed.

The flaw detector may further include a regulation unit attached to theprobe. Therefore, it is possible to perform flaw detection and to levelan upper surface of a laminate of the conductive powder while moving theprobe. The pair of detection coils may be disposed at positionsoverlapping each other in the first direction. Therefore, it is possibleto reduce the effect of noise and to accurately detect a flaw bycalculating a difference between signals detected by the pair ofdetection coils.

Hereinbelow, a preferred embodiment of the present disclosure will bedescribed in detail with reference to the drawings. Note that in thedrawings, the same reference signs will be assigned to the same orequivalent parts and duplicated descriptions will be omitted.

An apparatus 1 for producing a three-dimensional object by additivemanufacturing (hereinbelow, referred to as a “production apparatus”) ofa first embodiment illustrated in FIG. 1 is a so-called 3D printer, andproduces a three-dimensional component (three-dimensional multilayerobject) 3 by repeating a step of partially applying energy to a metallicpowder (conductive powder) 2 disposed in layers and thereby melting andcuring the metallic powder 2 a plurality of times.

The three-dimensional component 3 is, for example, a mechanicalcomponent, and may be other structures. Examples of the metallic powderinclude a titanium metal powder, an Inconel (registered trademark)powder, and an aluminum powder. The conductive powder is not limited toa metallic powder, and may be a powder such as carbon fiber reinforcedplastics (CFRP) containing carbon fiber and resin, or may be otherpowders having conductivity.

The production apparatus 1 includes: a work table (holding unit) 4; avertical position adjusting mechanism 5; a brush unit (regulation unit)6; a first moving mechanism (regulation unit moving mechanism) 7; and aradiation gun (energy application unit) 8.

The work table 4 forms, for example, a plate shape, and the metallicpowder 2 which is a raw material of the three-dimensional component 3 isdisposed on the work table 4. The metallic powder 2 is disposed, forexample, in layers a plurality of times on the work table 4. A laminateof the metallic powder 2 on the work table 4 is referred to as a powderbed 25. The work table 4 forms, for example, a rectangular shape in aplan view. The work table 4 is movable in a Z direction (verticaldirection), and sequentially descends in response to the number oflayers of the metallic powder 2. A guide portion 9 guiding the movementof the work table 4 is provided at an outer periphery of the work table4. The guide portion 9 forms a square tube shape so as to correspond tothe outer shape of the work table 4. The guide portion 9 having a squaretube shape and the work table 4 form an accommodation portion thataccommodates the powder bed 25 forming a box shape. The work table 4 ismovable in the Z direction inside the guide portion 9.

The vertical position adjusting mechanism 5 is, for example, a rack andpinion type driving mechanism, and moves the work table 4 in the Zdirection. The vertical position adjusting mechanism 5 contains avertical member (rack) 10 having a bar shape which is connected to abottom surface of the work table 4 and extends downward, and a drivingsource 11 for driving the vertical member 10.

For example, an electric motor can be used as the driving source 11. Apinion is provided on an output shaft of the electric motor, and a toothprofile meshing with the pinion is provided on a side surface of thevertical member 10. If the electric motor is driven, the pinion rotatesto transmit power, and thus the vertical member 10 moves in the verticaldirection. When the rotation of the electric motor is stopped, thevertical member 10 is positioned, and the position of the work table 4in the Z direction is determined and the position is held. The verticalposition adjusting mechanism 5 is not limited to a rack and pinion typedriving mechanism, but may include other driving mechanisms such as aball screw and a cylinder. The vertical position adjusting mechanism 5is capable of descending the holding unit, and holding the position ofthe holding unit in the vertical direction.

The brush unit 6 is disposed above the work table 4, and levels asurface (upper surface) 2 a of an uppermost layer of the powder bed 25placed on the work table 4. The brush unit 6 is movable in a Y direction(first direction) intersecting the Z direction, and levels the surface 2a of the powder bed 25. A lower end portion of the brush unit 6 comesinto contact with the surface 2 a of the powder bed 25 to level thesurface 2 a at a uniform height. The brush unit 6 has a predeterminedwidth in an X direction (second direction), and corresponds to theentire length of the work table 4 in the X direction. The X direction isa direction intersecting the Z direction and the Y direction. Theproduction apparatus 1 may be configured to include other regulationunits such as a roller unit and a plate-shaped member instead of thebrush unit 6. The regulation unit may be any type of member capable ofleveling the surface of the powder bed 25.

The first moving mechanism 7 is, for example, a rack and pinion typedriving mechanism, and moves the brush unit 6 in the Y direction. Thefirst moving mechanism 7 contains a pair of guide rails 12 on both sidesin the X direction which extend in the Y direction, and a driving source13 attached to the brush unit 6. In the embodiment, an applicationmechanism applying the powder contains the regulation unit and the firstmoving mechanism. The first moving mechanism 7 relatively moves thebrush unit 6 with respect to the powder bed 25.

For example, an electric motor can be used as the driving source 13. Apinion is provided on an output shaft of the electric motor, and a toothprofile (rack) meshing with the pinion is provided on one guide rail 12.The pair of guide rails 12 are attached to, for example, a housing(frame body) of the production apparatus 1. A driven roller rotationallymoving along the other guide rail 12 is attached to the brush unit 6. Ifthe electric motor is driven, the pinion rotates, and thus the brushunit 6 moves along the guide rail 12 in the Y direction.

The radiation gun 8 melts the metallic powder 2 by irradiating themetallic powder 2 with radiation from above the work table 4. Theradiation gun 8 is movable to a predetermined position, and locallymelts the metallic powder 2 by radiating radiation corresponding to theposition. The radiation gun 8 radiates radiation as energy beams. Theproduction apparatus 1 may be configured to include other energyapplication units instead of the radiation gun 8. The energy beams maybe charged particle beams such as electron beams, or may be laser beams.The energy application unit melts the conductive powder, for example, byelectron beam melting (EBM), but the energy application unit is notlimited to employing the electron beam melting. For example, the energyapplication unit may employ selective laser melting (SLM) in which theconductive powder is melted by irradiating the conductive powder withlaser beams as energy beams, or selective laser sintering (SLS) in whichthe conductive powder is sintered by irradiating the powder with laserbeams. The energy application unit may melt or sinter and solidify(cure) the conductive powder by applying energy to the conductive powderby other methods and thereby heating the conductive powder.

The production apparatus 1 contains a control unit 14 controlling theproduction apparatus 1. The control unit 14 controls the verticalposition adjusting mechanism 5, the first moving mechanism 7, and theradiation gun 8. The control unit 14 is a computer formed of hardwaresuch as a central processing unit (CPU), a read only memory (ROM), and arandom access memory (RAM) and software such as a program stored in theROM. The control unit 14 controls the position of the work table 4 inthe Z direction by controlling the vertical position adjusting mechanism5. The control unit 14 controls the movement of the brush unit 6 bycontrolling the first moving mechanism 7. The control unit 14 controls aradiation irradiation position and a radiation irradiation time bycontrolling the radiation gun 8.

Herein, as illustrated in FIG. 2, the production apparatus 1 contains aflaw detection device (flaw detector) 15 detecting a flaw in a surfacelayer portion 3 a of the three-dimensional component 3. The flawdetection device 15 includes: a probe 16; a calculation unit 17; a powersupply circuit 18; and a display unit 19.

The probe 16 is attached to the brush unit 6, and is movable in the Ydirection along with the brush unit 6. The first moving mechanism 7serves also as a probe moving mechanism moving the probe 16 in the Ydirection. A bottom surface 16 a of the probe 16 is disposed higher thana lower end 6 a of the brush unit 6. A gap is formed between the bottomsurface 16 a of the probe 16 and the surface 2 a of the powder bed 25.The probe 16 is not in contact with the metallic powder 2 and thethree-dimensional component 3. The probe 16 is disposed behind the brushunit 6 in the scanning direction. The scanning direction is, forexample, a direction from a left side toward a right side in FIGS. 1 and2. Note that the scanning direction is not limited to the direction butmay be any direction.

As illustrated in FIG. 3, the probe 16 extends in the X directionintersecting the Y direction which is the scanning direction. The probe16 contains a plurality of coil units 20 disposed side by side in the Xdirection. For example, eight coil units 20 are disposed in the Xdirection. In the probe 16, the plurality of coil units 20 disposed sideby side in the X direction forms one row. The plurality of coil units 20forms a row along each of virtual straight lines X1 to X4 extending inthe X direction. In the probe 16, a plurality of rows (for example, fourrows) of the coil units 20 are disposed side by side in the Y direction.The virtual straight lines X1 to X4 are disposed spaced apart from eachother in the Y direction. The probe 16 includes, for example, 32 coilunits 20 in total. The coil units 20 of the probe 16 are accommodated ina case forming, for example, a box shape.

A plurality of the coil units 20 are disposed along a virtual straightline T. The straight line T is obliquely disposed with respect to the Xdirection and the Y direction. The plurality of coil units 20, forexample, four coil units 20 are disposed along the straight line T. Theplurality of coil units 20 are disposed at different positions in the Xdirection, respectively. The plurality of coil units 20 may be disposedwithout gaps therebetween when seen from the Y direction.

In FIG. 3, virtual straight lines Y1 to Y4 extending in the Y directionare illustrated. The straight lines Y1 to Y4 are disposed spaced apartfrom each other in the X direction. A coil unit 20A is disposed at anintersection point between the straight line X1 and the straight lineY1. A coil unit 20B is disposed at an intersection point between thestraight line X2 and the straight line Y2. A coil unit 20C is disposedat an intersection point between the straight line X3 and the straightline Y3. A coil unit 20D is disposed at an intersection point betweenthe straight line X4 and the straight line Y4. The plurality of coilunits 20 contain the coil units 20A to 20D. One coil unit 20 is disposedon each of the straight lines Y1 to Y4. In the probe 16, another coilunit 20 is not disposed behind the coil unit 20 in the scanningdirection. The straight lines X1 to X4 are disposed in the order of X4,X3, X2, and X1 in the Y direction. The straight lines Y1 to Y4 arerepeatedly disposed in the order of Y4, Y3, Y2, and Y1 in the Xdirection. Gaps between the straight lines X1 to X4 are wider than gapsbetween the straight lines Y1 to Y4. Gaps between the straight lines Tin the X direction are wider than the gaps between the straight lines X1to X4.

As illustrated in FIG. 4, the coil unit 20 includes an excitation coil21; a pair of detection coils 22; and ferrite cores (iron cores) 23. Theexcitation coil 21 is supplied with an alternating current from thepower supply circuit 18 to generate a magnetic field, and to generate aneddy current in the surface layer portion 3 a of the three-dimensionalcomponent 3. For example, the excitation coil 21 is formed around anaxis line extending in the Z direction.

The pair of detection coils 22 are disposed inside the excitation coil21. For example, the detection coil 22 is formed around an axis lineextending in the Z direction. The ferrite core 23 is disposed inside thedetection coil 22. The ferrite core 23 forms, for example, a bar shapeand extends in the Z direction. The ferrite core 23 may have a columnarshape, or may have a prismatic shape.

When seen from the Z direction, the pair of detection coils 22 aredisposed adjacent to each other in the Y direction in a state where thepositions thereof in the X direction are offset from each other suchthat portions thereof overlap each other in the X direction. Namely,when seen from the Y direction, the pair of detection coils 22 aredisposed such that portions thereof overlap each other and remainingportions do not overlap each other in the X direction. The pair ofdetection coils 22 detect a change in the magnetic field induced by theeddy current of the surface layer portion 3 a.

If there is a flaw in the surface layer portion 3 a, a change occurs inthe flow of the eddy current, and thus the magnetic field becomeschanged. Therefore, it is possible to detect whether or not there is aflaw by detecting a change in the magnetic field with the detectioncoils 22. If one of the pair of detection coils 22 detects a change inthe magnetic field and the other does not detect a change in themagnetic field, it is possible to accurately detect a change in themagnetic field by calculating a difference between signals detected bythe pair of detection coils 22. Since the difference between the signalsbecomes the maximum when the probe passes by above the flaw, it ispossible to prevent electrical noise and accurately detect the flaw bycalculating the difference between the signals detected by the pluralityof detection coils 22.

A flaw detected by the detection coils 22 is, for example, a weldpenetration defect, a crack, a fusion, a porosity (void), or the like.

The calculation unit 17 is electrically connected to the pair ofdetection coils 22, and calculates a difference between signals detectedby the pair of detection coils 22. The calculation unit 17 is a computerformed of hardware such as a CPU, a ROM, and a RAM and software such asa program stored in the ROM. The calculation unit 17 may be configuredseparately from the control unit 14, and may be configured to becontained in the control unit 14.

The power supply circuit 18 supplies an alternating current to theexcitation coil 21. The frequency of the alternating current supplied tothe excitation coil 21 may be, for example, 500 kHz to 2 MHz, or may beother frequencies. An eddy current is generated in the surface layerportion 3 a of the three-dimensional component 3 by supplying analternating current to the excitation coil 21. The surface layer portion3 a contains the surface and an inner portion in the vicinity of thesurface of the three-dimensional component 3, for example, may contain aregion from the surface to a depth of 1 mm. The surface layer portionmay contain a region, for example, to a depth of 2 mm, or may contain aregion to other depths. The probe 16 is capable of detecting a flaw in aregion to the depth of a plurality of layers (for example, five layers)of the metallic powder 2, which are equivalent to the surface layerportion 3 a of the three-dimensional component 3.

The display unit 19 displays image information regarding a flawdetection result output from the calculation unit 17. The display unit19 is capable of displaying a position where a flaw is present and aposition where no flaw is present by using color gradations. Each ofFIGS. 5 and 6 illustrates one example of image information regarding aflaw detection result. FIGS. 5 and 6 illustrate results of detectingflaws in test pieces, each of which contains a flaw provided in asurface layer portion. In FIGS. 5 and 6, a region where a differencebetween detected signals is large is illustrated dark. For example, inFIG. 5, a flaw is present at a position 75 mm in the X direction and 65mm in the Y direction from the origin, and in FIG. 6, a flaw is presentat a position 60 mm in the X direction and 30 mm in the Y direction fromthe origin. Since a difference between signals is large even with ashape discontinuity, in FIGS. 5 and 6, the shape discontinuity isillustrated in dark color.

Subsequently, a method for producing a three-dimensional component(method for producing a three-dimensional multilayer object) will bedescribed. FIG. 7 is a flowchart illustrating a procedure of the methodfor producing a three-dimensional component. The method for producing athree-dimensional component is executed using, for example, theproduction apparatus 1.

In the embodiment, firstly, a powder layer as a first layer is to beformed. Herein, the metallic powder 2 for the first layer is suppliedonto the work table 4, and the surface 2 a of the powder bed 25 isleveled by moving the brush unit 6 in the Y direction (Step S1). Step S1contains an application step of applying the metallic powder 2. Themetallic powder 2 is supplied onto the work table 4 from, for example, apowder storage tank not illustrated.

Subsequently, a melting step (energy application step) of melting themetallic powder 2 on the work table 4 by irradiating the metallic powder2 with radiation is performed (Step S2). Instead of the melting step, asintering step (energy application step) of sintering the conductivepowder by partially applying energy to the conductive powder may beperformed. A preheating step of raising the temperature of the metallicpowder 2 by applying energy to the metallic powder 2 may be executed,for example, after the application step (Step S1) and before the energyapplication step (Step S2). After Step S2 has ended, the work table 4 isdescended (Step S3). A space for adding the metallic powder 2 for asecond layer is secured by descending the work table 4.

Subsequently, a powder layer as a second layer (n+1^(th) layer) is to beformed. Herein, after the metallic powder 2 of the first molten layer(n^(th) layer) has been cured, the metallic powder 2 for the secondlayer (n+1^(th) layer) is supplied onto the work table 4 (onto themetallic powder of the n^(th) layer), and the surface 2 a of a laminate(n+1^(th) layer) of the metallic powder 2 is leveled by moving the brushunit 6 in the Y direction (Step S4). Step S4 contains the applicationstep of applying the metallic powder 2. At that time, a flaw detectionstep (Step S5) is executed when the brush unit 6 is moved. For example,along with leveling the surface 2 a of the metallic powder 2 of thesecond layer (n+1^(th) layer), the flaw detection step is executed forthe surface layer portion 3 a of the first layer (n^(th) layer).

In the flaw detection step, an excitation step and a detection step areperformed. The flaw detection step may be executed for, for example, onelayer of the surface layer portion 3 a. The flaw detection step may beexecuted for, for example, a plurality of layers (two to four layers) ofthe surface layer portion 3 a. For example, after the surface layerportion 3 a containing a plurality of layers has been shaped byrepeatedly performing the melting step (energy application step), thework table descending step, and the step of leveling the metallic powdera plurality of times, the flaw detection step may be collectivelyperformed on the plurality of layers of surface layer portion 3 a. Themelting step, the work table descending step, and the step of levelingthe metallic powder are performed a plurality of times, for example,when a final step of leveling the metallic powder is performed, the flawdetection step may be collectively performed on the plurality of layersof surface layer portion 3 a.

In the excitation step, the excitation coil 21 is supplied with currentto generate a magnetic field, and to generate an eddy current in thesurface layer portion 3 a. In the excitation step, the order ofexcitation may be changed for a plurality of the excitation coils 21. Inthe excitation step, the order of excitation may be changed, forexample, depending on the positions of the excitation coils 21 in thescanning direction. In the excitation step, the order of excitation mayset for the coil units 20 on the straight lines X1 to X4 illustrated inFIG. 3.

In the excitation step, the excitation coils 21 may be excited, forexample, in the order of the coil unit 20A on the straight line X1, thecoil unit 20B on the straight line X2, the coil unit 20C on the straightline X3, and the coil unit 20D on the straight line X4. The order ofexciting the excitation coils 21 may be other orders. The excitationcoils 21 may be excited, for example, in the order of the coil unit 20Aon the straight line X1, the coil unit 20C on the straight line X3, thecoil unit 20B on the straight line X2, and the coil unit 20D on thestraight line X4.

The plurality of coil units 20 disposed side by side on the samestraight line among the straight lines X1 to X4 may be excited at thesame time. Namely, for example, a plurality of the coil units 20A on thestraight line X1 are initially excited at the same time. Subsequently, aplurality of the coil units 20B on the straight line X2 are excited atthe same time. Subsequently, a plurality of the coil units 20C on thestraight line X3 are excited at the same time. Subsequently, a pluralityof the coil units 20D on the straight line X4 are excited at the sametime. Hereinbelow, the same excitation may be repeatedly performed.

If a gap (gap between the straight lines T in the X direction) betweenthe coil units 20 adjacent to each other on the same straight line amongthe lines X1 to X4 is a sufficient distance, even though the adjacentcoil units 20 are excited at the same time, it is possible to preventthe coil units 20 from having adverse electromagnetic effects ondetections thereof.

In the detection step, a change in the magnetic field in the surfacelayer portion 3 a is detected. In the detection step, a change in themagnetic field induced by the eddy current of the surface layer portion3 a is detected. For example, if there is a flaw, a shape discontinuity,or the like in the surface layer portion 3 a, the eddy current bypassesthe flaw, the shape discontinuity, or the like and is changed, and themagnetic field is changed.

In the detection step, the calculation unit 17 calculates a differencebetween signals detected by the pair of detection coils 22. Thecalculation unit 17 generates image information indicating a detectionresult, based on a result of the calculation. The image informationindicating the detection result is output to and on the display unit 19.The position, size, orientation, and the like of a flaw may be displayedin the image information indicating the detection result.

Subsequently, based on the detection result, it is determined whether ornot there is a flaw (Step S6). Herein, based on the difference betweenthe signals detected by the pair of detection coils 22, the calculationunit 17 may determine whether or not there is a flaw, or a user maydetermine whether or not there is a flaw by watching the imageinformation displayed on the display unit 19.

If a flaw has not been detected, the process proceeds to Step S9, and ifa flaw has been detected, the process proceeds to Step S7.

In Step S7, a repair step is performed. Herein, for example, themetallic powder is supplied once again, and a flawed portion is meltedand cured. Thereafter, the flaw detection step is executed once again(Step S8). In the flaw detection step referred to herein, for example,similarly to Step S5, a flaw may be detected in the entire surface ofthe surface layer portion 3 a, or a flaw may be detected only in aregion corresponding to a repaired portion.

Subsequently, the process returns to Step S6 again, and it is determinedwhether or not there is a flaw. After it has been confirmed that thereis no flaw, the process proceeds to Step S9. In Step S9, the productionof the entire layers of the three-dimensional component 3 has ended, andit is determined whether or not the component has been completed. Forexample, it is determined whether or not the production of layers asdesigned has ended. If the production of the three-dimensional componenthas not ended, the process returns to Step S2. In Step S2, melting isperformed by partially applying energy to the metallic powder (powderlayer) of the second layer (n+1^(th) layer) formed in Step S4 describedabove. The production of the three-dimensional component 3 is performedby repeating the same steps thereafter.

The probe 16 of the flaw detection device 15 includes the plurality ofcoil units 20 disposed side by side in the X direction intersecting thescanning direction. The flaw detection device 15 is capable of detectingflaws in a wide range in the X direction and reducing a flaw detectiontime by moving the probe 16 in the scanning direction. Since it ispossible to detect a flaw in the surface layer portion 3 a of thethree-dimensional component 3 during production, it is possible toproduce the three-dimensional component 3 by further adding the metallicpowder 2 after having confirmed that there is no flaw in the surfacelayer portion 3 a. In the probe 16, the pair of detection coils 22 aredisposed side by side in the scanning direction, and are disposed atpositions overlapping each other in the Y direction. The flaw detectiondevice 15 is capable of reducing effects of noise and accuratelydetecting a flaw by calculating the difference between the signalsdetected by the pair of detection coils 22. If a flaw has been detectedin the surface layer portion 3 a, it is possible to produce thethree-dimensional component 3 by further adding the metallic powder 2after repairing the flaw. Therefore, it is not necessary to perform flawdetection after the production of the three-dimensional component 3 hasbeen completed, and to repair a flaw inside the three-dimensionalcomponent 3 based on a result thereof.

In the production apparatus 1, the bottom surface 16 a of the probe 16is disposed higher than the lower end 6 a of the brush unit 6.Therefore, it is possible to detect a flaw in the surface layer portion3 a of the three-dimensional component 3 in a state where the probe 16is in no contact with the metallic powder 2. Since the probe 16 is in nocontact with the metallic powder 2, it is possible to reduce the risk ofoccurrence of a flaw by preventing cracks of the added metallic powder2. Since the probe 16 is in no contact with the three-dimensionalcomponent 3, it is possible to reduce the risk of damage of thethree-dimensional component 3.

Since the probe 16 is disposed behind the brush unit 6 in the movementdirection of the brush unit 6, the probe 16 passes by above the metallicpowder 2 after the metallic powder 2 has been leveled by the brush unit6. For this reason, it is possible to further reduce the risk of theprobe 16 coming into contact with the metallic powder 2.

In the production apparatus 1, the probe 16 is attached to the brushunit 6, and thus the first moving mechanism 7 is capable of moving theprobe 16 along with the brush unit 6. Therefore, it is not necessary toseparately perform movement of the brush unit 6 and movement of theprobe 16, and to shorten a production time of the entire processcontaining the inspection step.

In the related art, there is a concern that due to reaction with metalin eddy current testing (ECT), the sensitivity of the probe is loweredby the metallic powder. However, the inventors have found that there isalmost no electrical connection between particles of the metallic powderand detection of a flaw in a surface layer portion of athree-dimensional component is not affected by the metallic powderaccumulated thereon.

In the probe 16, another coil unit 20 is not disposed behind one coilunit 20 on each of the straight lines Y1 to Y4 extending in the scanningdirection. Therefore, the excitation coil 21 and the detection coil 22positioned behind in the scanning direction have reduced effects onexcitation and detection, respectively. In the probe 16, the coil units20 are prevented from having adverse electromagnetic effects on eachother. For this reason, in the probe 16, a large number of the coilunits 20 are disposed, and thus it is possible to detect flaws in a widerange in the X direction.

In the excitation step, the order of excitation of the excitation coils21 is changed depending on the positions of the coil units 20A to 20D inthe scanning direction. Therefore, it is possible to preventinterference between the coil units 20 close to each other in thescanning direction. For example, excitation and detection performed bythe coil unit 20B are not easily affected by excitation and detectionperformed by the coil unit 20A close thereto. The coil units 20 areprevented from having adverse electromagnetic effects on each other byelaborating the order of excitation in the excitation step. For thisreason, a large number of the coil units 20 are disposed in the probe16, and thus it is possible to detect flaws in a wide range in the Xdirection.

In the above-mentioned first embodiment, the brush unit 6 and the probe16 are moved with respect to the powder bed 25; however, the brush unit6 and the probe 16 may be stopped and the powder bed 25 may be moved.For example, the work table 4 holding the powder bed 25 and thethree-dimensional component 3, and the guide portion 9 may be moved inthe X direction and the Y direction.

“Relatively moving the brush unit 6 with respect to the powder bed 25”contains “a case where the brush unit 6 is moved in a state where thework table 4 is stopped” and “a case where the work table 4 is moved ina state where the brush unit 6 is stopped”. “Relatively moving the probe16 with respect to the surface layer portion 3 a of thethree-dimensional component 3” contains “a case where the probe 16 ismoved in a state where the work table 4 is stopped” and “a case wherethe work table 4 is moved in a state where the probe 16 is stopped”.

Subsequently, a probe 31 according to a second embodiment will bedescribed with reference to FIG. 8. The probe 31 differs from the probe16 in that the length in the X direction and the number of the coilunits 20 differ therebetween. The probe 31 is short in the X directioncompared to the probe 16. In the probe 31, for example, four coil units20 are disposed in the X direction. In FIG. 8, virtual straight lines T1to T4 obliquely extending with respect to the X direction and the Ydirection are illustrated. Four coil units 20A to 20D are disposed oneach of the straight lines T1 to T4.

A flaw detection device including the probe 31 may include a probemoving mechanism moving the probe 31 in the X direction and the Ydirection. The probe moving mechanism contains a first guide railextending in the Y direction and a second guide rail extending in the Xdirection. The probe moving mechanism moves the second guide rail alongthe first guide rail, and moves the probe 31 along the second guiderail. The probe moving mechanism may be configured to include, forexample, a rack and pinion type driving mechanism. The probe movingmechanism may include other driving mechanisms, for example, a cylinder,a ball screw, or the like.

FIG. 9 is a plan view illustrating a movement path of the probe 31. Thepowder bed 25 follows the shape of the guide portion 9 and forms, forexample, a rectangular shape in a plan view. The three-dimensionalcomponent 3 is present in the powder bed 25. The length of the probe 31in the X direction is shorter than the length of the powder bed 25 inthe X direction. The length of the probe 31 in the Y direction isshorter than the length of the powder bed 25 in the Y direction. In FIG.9, the movement path of the probe 31 is illustrated by arrows.

Before the start of the flaw detection step, the probe 31 is disposed ata position corresponding to one corner portion of the powder bed 25. Inthe flaw detection step, the excitation step and the detection step areexecuted by moving the probe 31 in the X direction. The probe 31 ismoved by the length of the powder bed 25 in the X direction.Subsequently, the probe 31 is moved in the Y direction. The probe 31 ismoved, for example, corresponding to the length of the probe 31 in the Ydirection. Subsequently, the probe 31 is moved in a direction oppositeto the previous movement direction in the X direction. The excitationstep and the detection step are executed during this movement. The probe31 is moved in the Y direction again. As described above, the excitationstep and the detection step are executed while moving the probe 31.Herein, the excitation step and the detection step are executed for, forexample, the entire area of the powder bed 25. The movement path of theprobe is not limited to being aligned along a straight line, and may becurved along an arc. In the flaw detection step, the powder bed 25 isstopped, and the probe 31 is moved. Therefore, the probe 31 isrelatively moved with respect to the powder bed 25.

In the excitation step, for example, if the probe 31 is moved in the Xdirection (toward the right), it is possible to perform excitation ofthe excitation coils 21 in the order of the coil units 20 on thestraight line T1, the coil units 20 on the straight line T2, the coilunits 20 on the straight line T3, and the coil units 20 on the straightline T4 illustrated in FIG. 8. Similarly, in the excitation step, if theprobe 31 is moved oppositely (toward the left) in the X direction, it ispossible to perform excitation of the excitation coils 21 in the orderof the coil units 20 on the straight line T4, the coil units 20 on thestraight line T3, the coil units 20 on the straight line T2, and thecoil units 20 on the straight line T1. In the excitation step,excitation may be performed in other orders.

The movement path of the probe 31 is not limited to the movement pathillustrated in FIG. 9. For example, a movement path in the followingmodification example may be employed. Before the start of the flawdetection step, the probe 31 is disposed at a position corresponding toone corner portion of the powder bed 25. In the flaw detection step, theexcitation step and the detection step are executed by moving the probe31 in the Y direction. The probe 31 is moved by the length of the powderbed 25 in the Y direction. Subsequently, the probe 31 is moved in the Xdirection. The probe 31 is moved, for example, corresponding to thelength of the probe 31 in the X direction. Subsequently, the probe 31 ismoved in a direction opposite to the previous movement direction in theY direction. The excitation step and the detection step are executedduring this movement. The probe 31 is moved in the X direction again. Asdescribed above, the excitation step and the detection step are executedwhile moving the probe 31. In this case, the order of excitation of thecoil units 20 may be the same order as that in the first embodiment.

FIG. 10 is a plan view illustrating another movement path of the probe31. In FIG. 10, the movement path of the probe 31 is illustrated byarrows. The three-dimensional component 3 is disposed in the powder bed25. The length of the three-dimensional component 3 in the X directionis not constant, but is changed depending on positions in the Ydirection. The length of the three-dimensional component 3 in the Ydirection is not constant, but is changed depending on positions in theX direction.

In the flaw detection step, the probe 31 may be moved according to theshape of the three-dimensional component 3. In the flaw detection step,for example, the probe 31 may not be moved over the entirety of thepowder bed 25. In the flaw detection step, the probe 31 may be movedcorresponding to only a portion where the three-dimensional component 3is present. As a modification example of the probe 31 illustrated inFIG. 8, the probe 31 may have a configuration where a plurality of thecoil units 20 are not disposed along the straight lines X1 to X4. Forexample, the probe may include a plurality of the coil units 20 disposedside by side along a plurality of straight lines inclined with respectto the X direction.

Subsequently, a production apparatus 41 according to a third embodimentwill be described with reference to FIG. 11. The production apparatus 41differs from the production apparatus 1 of the first embodiment in thata powder bed 42 having a circular shape is held, and in that a worktable holding the powder bed 42 rotates. In the description of theproduction apparatus 41, the same descriptions as those in theabove-mentioned embodiment will be omitted.

The production apparatus 41 includes the work table holding the powderbed 42 having a circular shape, and a guide portion 43. The guideportion 43 forms a cylindrical shape. The work table is disposed insidethe guide portion 43, and can be ascended and descended. Athree-dimensional component and the powder bed 42 are present on thework table. The production apparatus 41 contains a work table rotatingmechanism rotating the work table around a center O. The work tablerotating mechanism, for example, is capable of including an electricmotor, a rotary shaft, a gear, a power transmission belt, and the like.

The production apparatus 41 contains a powder supply unit (applicationmechanism) supplying (forming powder layers) the metallic powder 2 to asupply region on the work table (powder bed 42). The powder supply unitcontains the brush unit 6. The brush unit 6 extends from the center O ina radial direction of the work table. In the production apparatus 41, ifthe work table rotates, the powder bed 42 and the three-dimensionalcomponent move. The guide portion 43 rotates, for example, along withthe work table. In FIG. 11, a rotation direction R of the work table isillustrated by an arrow. The work table may rotate opposite to therotation direction R. The length of the brush unit 6 corresponds to, forexample, the radius length of the work table or the guide portion 43.The brush unit may be longer than, for example, the diameter of the worktable or the guide portion 43.

The production apparatus 41 contains an energy application unit.Similarly to the energy application unit in the first embodiment, theenergy application unit may be, for example, a radiation gun (electrongun) radiating electron beams as energy beams, or a laser irradiationunit radiating laser beams as energy beams. The energy application unitirradiates an irradiation region on the work table (powder bed 42) withenergy beams. The irradiation region is set downstream of the powdersupply unit in the rotation direction R.

The production apparatus 41 contains a flaw detection device 44including the probe 16. A longitudinal direction of the probe 16 isdisposed along the radial direction of the work table. The probe 16 isdisposed behind the brush unit 6 in the rotation direction R of the worktable. The length of the probe 16 in the X direction corresponds to, forexample, the radius length of the work table or the guide portion 43.The probe 16 may be longer than, for example, the diameter of the worktable or the guide portion 43. The length of the probe 16 may be, forexample, the same as the length of the brush unit 6, or may be shorterthan the length of the brush unit 6. The probe 16 may be attached to thebrush unit 6, or may be disposed at a position apart from the brush unit6. The probe 16 may serve as a regulation unit.

The production apparatus 41 is capable of repeatedly performing anenergy application step, a powder supply step (step of leveling an uppersurface of a conductive powder), and a flaw detection step in the ordermentioned. In the energy application step, the metallic powder 2 ismelted or sintered by applying energy to the metallic powder 2 whilerotating the work table. In the powder supply step, the metallic powder2 is supplied to the supply region on the work table. In the flawdetection step, a flaw may be detected in a surface layer portion of thethree-dimensional component on the work table.

In the production apparatus 41, the work table rotates, and thus it ispossible to relatively move the brush unit 6 with respect to the powderbed 42 on the work table. Therefore, it is possible to level a surfaceof the powder bed 42. Similarly, it is possible to relatively move theflaw detection device 44 with respect to the three-dimensional componenton the work table. Therefore, it is possible to detect a flaw in thethree-dimensional component using the probe 16. In this case, adirection opposite to the rotation direction R of the work table is ascanning direction. The scanning direction is a direction not alignedalong a straight line but along a curved line curved along an arc. Theprobe 16 may be configured to serve as the brush unit 6. The productionapparatus 41 relatively moves the brush unit 6 and the probe 16 withrespect to the powder bed 42 by rotating the work table, but may stopthe work table and move the brush unit 6 and the probe 16 with respectto the powder bed 42.

FIG. 12 is a plan view of a production apparatus 45 according to afourth embodiment. The production apparatus 45 differs from theproduction apparatus 41 of the third embodiment in that the productionapparatus 45 includes the probe 31 instead of the probe 16. Theproduction apparatus 45 contains a flaw detection device 46 includingthe probe 31. The probe 31 is the probe described in the above-mentionedsecond embodiment. The probe 31 is shorter than the brush unit 6 in alongitudinal direction (X direction illustrated). The probe 31 ismovable with respect to the brush unit 6 in the longitudinal direction.The production apparatus 45 may contain a probe moving mechanism movingthe probe 31 in the radial direction of the work table. The probe movingmechanism may include, for example, an electric motor, a hydrauliccylinder, a rack and pinion, a guide rail, a ball screw, and the like.

For example, the three-dimensional component 3 forming a cylindricalshape is disposed on the work table. The probe moving mechanism iscapable of moving the probe 31 above the three-dimensional component 3.In the flaw detection step, it is possible to detect a flaw in thethree-dimensional component 3 by rotating the work table and therebyrelatively moving the probe 31 with respect to the three-dimensionalcomponent 3. The flaw detection device 46 may detect a flaw in thethree-dimensional component 3 by relatively moving the probe 31 in acircumferential direction of the three-dimensional component 3.

FIGS. 13 and 14 are views illustrating a production apparatus 51according to a fifth embodiment. The production apparatus 51 differsfrom the production apparatus 41 of the third embodiment illustrated inFIG. 11 in that the powder bed 42 in which an opening portion is formedat a center is held. The opening portion formed at the center of thepowder bed 42 passes therethrough in the Z direction. The work table 4forms an annular shape in a plan view. The guide portion 43 includes anouter wall 43 a and an inner wall 43 b which form a cylindrical shape.The powder bed 42 and the three-dimensional component 3 are disposed ina region between the outer wall 43 a and the inner wall 43 b.

The production apparatus 51 includes a support portion 52 supporting thebrush unit 6 and the probe 16. The support portion 52 forms, forexample, a bar shape and extends in the Z direction. The support portion52 is disposed so as to pass through the opening portion at the centerof the powder bed 42. For example, an end portion of the probe 16adjacent to a central portion side is connected to the support portion52. The support portion 52 is disposed, for example, so as to be incontact with the inner wall 43 b in a plan view. For example, thesupport portion 52 may be disposed at the center O of the work table 4,or may be disposed outside the outer wall 43 a.

The production apparatus 51 is capable of rotationally moving the worktable 4 and the guide portion 43. The flaw detection device 44 iscapable of detecting a flaw in the powder bed 42 using the probe 16. Theprobe 16 may be configured to serve as the brush unit. The productionapparatus 51 may be configured to include the probe 31 instead of theprobe 16. The probe 31 is movable, for example, along the brush unit 6in a radial direction of the powder bed 42.

The present disclosure is not limited to the embodiments describedabove, and the following various modifications can be made withoutdeparting from the concept of the present disclosure.

In the above-mentioned embodiments, the configuration where the probe isattached to the regulation unit has been described; however, aconfiguration where the probe is not attached to the regulation unit maybe employed. The probe may be supported by other members, and may bemovable by the probe moving mechanism moving the probe in the scanningdirection. The scanning direction of the probe may be the same as themovement direction of the regulation unit, or may be a directionintersecting the movement direction of the regulation unit. The scanningdirection is not limited to one direction, and may be a plurality ofdirections. For example, a configuration where a plurality of the probeshaving different scanning directions are included may be employed.

A configuration where the probes are disposed on both sides in themovement direction of the regulation unit may be employed. For example,in FIG. 2, if the brush unit 6 moves to the right, it is possible toperform flaw detection with the probe 16 provided on the left side ofthe brush unit 6. If the brush unit 6 moves to the left, it is possibleto perform flaw detection with the probe 16 provided on the right sideof the brush unit 6.

In the above-mentioned embodiments, the probe is attached to theregulation unit; however, the probe may be attached ahead of theregulation unit, or may be built into the regulation unit. The probeitself may function as the regulation unit leveling the conductivepowder. The probe may be disposed spaced apart from thethree-dimensional multilayer object and may be in no contact therewith.

In the above-mentioned embodiments, the work table 4 has a rectangularshape; however, the work table 4 is not limited to having a rectangularshape. The production apparatus 1 may include, for example, a work tablehaving a circular shape and a guide portion having a circular shape, andmay contain an accommodation portion having a circular shape formed bythe work table and the guide portion.

A mechanism forming powder layers in Steps S1 and S4 is not limited tothe mechanisms in the above-mentioned embodiments. The regulation unitmay regulate the amount of the conductive powder to be supplied at aconstant value, and be able to level a surface of a laminate. Forexample, the production apparatus 1 may have a configuration where asupply unit supplying a constant amount of the conductive powder whilemoving in one direction is included and the probe is attached to thesupply unit. For example, a configuration where powder layers are formedand in parallel, flaw detection is performed by the flaw detector bysupplying the powder while moving the supply unit above the work table 4in the first direction may be employed.

The probe is not limited to being attached to the regulation unit. Theprobe may perform flaw detection while moving following the movement ofthe regulation unit. The probe may move regardless of the movement ofthe regulation unit. The production apparatus may not include theregulation unit.

The production apparatus and the production method of the presentdisclosure are not limited to being applied to a powder bed method. Theproduction apparatus and the production method may be applied to apowder deposition method. In this case, it is possible to provide theprobe in a material ejection unit (nozzle) ejecting the conductivepowder (material). It is possible to move the probe along with thematerial ejection unit. Therefore, after the conductive powder has beenejected from the material ejection unit and melted or sintered, it ispossible to perform flaw detection with the probe.

In the powder deposition method, the probe is not limited to beingattached to the material ejection unit. For example, a configurationwhere the probe moving mechanism moving the probe and a materialejection unit moving mechanism moving the material ejection unit areseparately included may be employed. For example, a configuration wherethe probe is disposed at a position apart from the material ejectionunit may be employed. Therefore, even though the temperature of thematerial ejection unit rises when beams are radiated, it is possible toprevent the transmission of heat from the material ejection unit to theprobe. As a result, the temperature rise of the probe is prevented. Theprobe may perform flaw detection while moving following the movement ofthe material ejection unit. The probe may move, for example, regardlessof the movement of the material ejection unit.

In the above-mentioned embodiments, the probe 16 (flaw detector)including the pair of detection coils 22 disposed inside the excitationcoil 21 at positions overlapping each other in the scanning directionhas been described; however, the pair of detection coils 22 may not bedisposed at positions overlapping each other in the scanning direction.The pair of detection coils 22 may be disposed at positions overlappingeach other in a direction intersecting the scanning direction. The factthat positions overlap each other in the scanning direction contains acase where the pair of detection coils 22 are disposed such thatportions thereof overlap each other in the scanning direction. Forexample, the central positions of the pair of detection coils 22 may notbe disposed at the same positions in the direction intersecting thescanning direction. The flaw detector may have a configuration wherethree or more detection coils 22 are disposed inside the excitation coil21.

In the above-mentioned embodiments, the production apparatuses 1, 41,45, and 51 and the method for producing a three-dimensional multilayerobject using the probes 16 and 31, in each of which the pair ofdetection coils 22 are disposed inside the excitation coil 21, have beendescribed. However, in the production apparatuses 1, 41, 45, and 51 andthe method for producing a three-dimensional multilayer object, it ispossible to perform flaw detection using other probes. For example, flawdetection may be performed using a probe including one detection coildisposed inside the excitation coil, or flaw detection may be performedusing a probe including the detection coil disposed outside theexcitation coil.

INDUSTRIAL APPLICABILITY

According to some aspects of the present disclosure, it is possible toprovide the apparatus for producing a three-dimensional multilayerobject, the method for producing a three-dimensional multilayer object,and the flaw detector capable of detecting a flaw in a three-dimensionalmultilayer object during the production of the three-dimensionalmultilayer object.

REFERENCE SIGNS LIST

1, 41, 45, 51: production apparatus (apparatus for producing athree-dimensional multilayer object), 2: metallic powder (conductivepowder), 3: three-dimensional component (three-dimensional multilayerobject), 3 a: surface layer portion, 4: work table (holding unit), 5:vertical position adjusting mechanism, 6: brush unit (regulation unit),7: first moving mechanism (regulation unit moving mechanism and probemoving mechanism), 8: radiation gun (energy application unit), 15: flawdetection device, 16, 31: probe (flaw detector), 16 a: bottom surface ofprobe, 20: coil unit, 21: excitation coil, 22: detection coil, 23:ferrite core (iron core), 25, 42: powder bed (laminate of metallicpowder), X: X direction (second direction), Y: Y direction (firstdirection), Z: Z direction (vertical direction).

1. A flaw detector that detects a flaw in a surface layer portion of athree-dimensional multilayer object during production, the detectorcomprising: a probe extending in a second direction intersecting a firstdirection which is a scanning direction, wherein the probe contains aplurality of coil units disposed side by side in the second direction,and wherein each of the coil units includes an excitation coilgenerating an eddy current in the surface layer portion, and a pair ofdetection coils disposed side by side inside the excitation coil.
 2. Theflaw detector according to claim 1, further comprising: a regulationunit attached to the probe.
 3. The flaw detector according to claim 1,wherein the pair of detection coils are disposed at positionsoverlapping each other in the first direction.